Abstract
Most glaciers in South America and on the Antarctic Peninsula are retreating and thinning. They are considered strong contributors to global sea level rise. However, there is a lack of glacier mass balance studies in other areas of the Southern Hemisphere, such as the surrounding Antarctic Islands. Here, we present a detailed quantification of the 21st century glacier elevation and mass changes for the entire South Georgia Island using bi-static synthetic aperture radar interferometry between 2000 and 2013. The results suggest a significant mass loss since the beginning of the present century. We calculate an average glacier mass balance of −1.04 ± 0.09 m w.e.a−1 and a mass loss rate of 2.28 ± 0.19 Gt a−1 (2000–2013), contributing 0.006 ± 0.001 mm a−1 to sea-level rise. Additionally, we calculate a subaqueous mass loss of 0.77 ± 0.04 Gt a−1 (2003–2016), with an area change at the marine and lake-terminating glacier fronts of −6.58 ± 0.33 km2 a−1, corresponding to ∼4% of the total glacier area. Overall, we observe negative mass balance rates in South Georgia, with the highest thinning and retreat rates at the large outlet glaciers located at the north-east coast. Although the spaceborne remote sensing dataset analysed in this research is a key contribution to better understanding of the glacier changes in South Georgia, more detailed field measurements, glacier dynamics studies or further long-term analysis with high-resolution regional climate models are required to precisely identify the forcing factors.
Highlights
IntroductionGlaciers on Earth are important components of the climate system
There is a lack of glacier mass balance studies in other areas of the Southern Hemisphere, including the surrounding Antarctic Islands
We provide for the first time the island-wide glacier elevation and mass changes of South Georgia between and 2013
Summary
Glaciers on Earth are important components of the climate system. Their changes are indicators of climate change and they contribute to global sea level rise (e.g. Forsberg et al2017; Rignot et al 2019; Wouters et al 2019). Farías-Barahona et al Antarctic Peninsula (Rott et al 2014; Rott et al 2018) and Patagonia (e.g. Malz et al 2018; Braun et al 2019), less is known about the glaciers located on the sub-Antarctic islands and the potential impacts of atmospheric warming on their retreat during the 20th and 21st centuries. South Georgia is the largest sub-Antarctic island South Georgia has a maritime climate which is dominated by its proximity to the Antarctic Polar Front and the strong westerly winds (and associated moisture flux) that strike the island (Graham et al2017). The annual mean temperature and precipitation are 2.0° C and 1590 mm, respectively (Bannister and King, 2019), with strong winds (in excess of ms-1) reported at King Edward Point Research Station
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